AirHint found the following cheapest return flights from Athens (ATH) to Ljubljana (LJU) in September 2025 (see full year).

Return flights

26 Sep - 30 Sep	Air Serbia
12 Sep - 19 Sep	Air Serbia
26 Sep - 29 Sep	Air Serbia
26 Sep - 28 Sep	Air Serbia
07 Sep - 12 Sep	Air Serbia
05 Sep - 09 Sep	Air Serbia
05 Sep - 08 Sep	Air Serbia
12 Sep - 16 Sep	Air Serbia
07 Sep - 07 Sep	Air Serbia
25 Sep - 29 Sep	Air Serbia
30 Sep - 10 Oct	Air Serbia
28 Sep - 07 Oct	Wizz Air Malta
29 Sep - 03 Oct	Air Serbia
27 Sep - 07 Oct	Air Serbia
30 Sep - 10 Oct	Aegean Airlines	direct
30 Sep - 03 Oct	Aegean Airlines	direct

Also check the deals for one-way flights from Athens to Ljubljana in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Athens to Ljubljana in September from 157€

Return flights